1. Field of the Invention
The present invention is directed to the field of electrical connectors and in particular the design of a female connector configured as a hyperboloid of revolution and the method of fabricating the connector.
2. Description of the Prior Art
Female electrical connectors or sockets configured by a plurality of flexible beam elements to take on the geometric shape of a hyperboloid of revolution are well known in the connector industry. In the hyperboloid, a three dimensional geometric shape having the appearance of an hour glass, the surface is generated by a plurality of straight line beam elements or generatrices. The diameter at the narrowest point of a cross section called the throat is smaller than the diameter of the inserted male member or pin causing spacial interference therebetween. As a result, the beams must deflect outward creating a contact force between the pin and the socket.
Several types of such sockets are shown in prior art patents. In one construction, the surface of a cylindrical tube is milled or sawn to form slots in the central section of the tube leaving a plurality of beam elements defined by the material remaining after the machine cuts. These beams may be straight as elements of a cylinder or partially wrap helix-like around the surface of the tube at an angle skewed with the longitudinal axis. The tube is then formed into the final shape of the desired socket by applying torsional forces at the ends of the tube to twist the beams into a hyperboloid-like shape. This torsional action is transmitted through every beam element of the connector which, in turn, twists each beam and allows the machined edges to come into contact with an inserted male pin member thus making for a generally inferior electrical connection. Such devices are disclosed in U.S. Pat. No. 2,450,529 to Sprigg and U.S. Pat. No. 4,480,587 to Lancella and U.S. Pat. No. 4,447,108 to Ghiglotti et. al.
In another type of hyperboloid connector, a plurality of wire beams is secured to a pair of end rings or ferrules. In U.S. Pat. No. 3,107,966 to Bonhomme, the wire elements are stretched within the diameter of a rigid tube attached to the ferrules to form the hyperboloid configuration of the connector. The rigid tube is required in order to keep the assembly from collapsing under the tension forces induced in the wires. This construction utilizes a large number of components with the concomitant high assembly costs. In another U.S. Pat. No. to Bonhomme (4,203,647), a similar construction is employed including the multiplicity of wires this time initially positioned as elements of a cylinder, and an equivalent rigid member for assuring the integrity of the connector configuration. This assembly is then loaded in torsion by twisting forces applied to the ferrules repositioning the wires into the hyperboloid configuration. Both of the Bonhomme patents form a connector having line contact between the round male pin and the round wire beam resulting in a less efficient, high resistance electrical contact since a round wire beam is only conformable to a round pin along a line of contact.
Another method is revealed in U.S. Pat. No. 1,833,145 to Wilhelm. Wilhelm punches a plurality of parallel and equally spaced slots into a flat blank of sheet metal that will be configured into the beams of the connector. The blank is then formed into a tube having the slots disposed longitudinally and parallel to the axis of the tube. The final step in Wilhelm's method is to twist the tube in order to position the beams as elements of a hyperboloid. As previously explained, this operation also exposes sheared edges to create high resistance at the interface with the inserted pin member.
These prior art devices either comprise a multiplicity of components or a necessary final step of twisting the tube to form a socket having the required hyperboloid configuration. Not only does this twisting action require an additional step in the fabrication process, it also places the beams in torsion thereby distorting them along the longitudinal axis, so efficient contact with the inserted pin is precluded.